This invention relates to the automated testing of illumination devices without the need for human operators, such as the testing of the plurality of illumination devices that are present in a telephone station set when the telephone station set is undergoing burn-in and/or environmental stress testing.
It is a problem in the field of automated testing of units under test to perform the necessary tests when the unit under test is undergoing burn-in and/or environmental stress testing. For example, a typical unit under test, such as a telephone station set is equipped with a plurality of illumination devices, such as red and green light emitting diodes, which must be tested to ensure their proper operation during the manufacturing process. The basic operation of these illumination devices can be determined by human operator inspection of the telephone station set during the routine unit test process. However, when the telephone station set is subjected to burn-in and/or environmental stress testing, the human operator is unable to access the telephone station set to determine the operational state of the illumination devices that are contained in the telephone station set. It is impractical to attempt to add apparatus to measure the light output of the illumination devices during the test process due to the difficulty of maintaining such test apparatus in alignment with the illumination devices during the test process. It is also costly to provide and interconnect such apparatus to the unit under test due to the hostile nature of the test environment. Therefore, dynamic testing of illumination devices during burn-in and/or environmental stress testing is presently not done.
However, it is desirable to identify not only the failure of an illumination device but also the conditions surrounding its failure. Collecting failure data relating to the reliability and failure modes of the illumination devices enable the manufacturer to increase the reliability of the telephone station set by identifying conditions which increase the probability of failure of the illumination devices. The inability of a manufacturer to identify the weaknesses in the unit under test results in increased number of failures.
There is presently no test apparatus that enables the manufacturer of a unit under test which contains illumination devices to determine the operational state of the illumination devices when the unit under test is undergoing burn-in and/or environmental stress testing. The automation of such tests and the ability to determine the operational state of illumination devices non-visually therefore represents a presently unmet need in the industry.
The above-described problems are solved and a technical advance achieved in the field by the present system for remote and non-visual detection of illumination device operation which is operational to identify the operational state of individual illumination devices. This is accomplished by placing the unit under test in a steady state operating condition during the burn-in and/or environmental stress testing process. The illumination devices are then individually selected and operated during the test and the operational state of the selected illumination device determined. The determination of the operational state of the illumination device is effected by measuring the incremental change in power drawn by the unit under test resulting from the activation of the selected illumination device. An anomaly in the measured change in power consumption is indicative of a failure mode for the selected illumination device. Where the unit under test contains a plurality of illumination devices, the illumination devices can be checked seriatim and the type of illumination device can also be determined by the power consumption of the activated illumination device to thereby identify misinstallation of illumination devices.